Used interrupts on both 68k & PIC, want 68k w/onboard memory & JTAG/BDM

Gentlemen -

The subject line says it all. I've just started looking around for a 68k-ish creature with some PIC-like features that might have popped up recently. Has anyone here seen this beast? Where?

2Penny (my 2 cents worth)
Reply to
2Penny
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Well not sure what PIC-like features means, but if you are after a tiny MCU with a reasonably powerful 68k (50 MHz), have a look at the coldfire line, the MCF51QE (IIRC the name) is available and there are another few similar ones promised.

Didi

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Reply to
Didi

It's called ColdFire now. Look at Freescale's website for all the data you could hope to get - there are plenty of CF parts with on-chip flash and RAM and all of them have embedded debug (JTAG).

I can give you gratis an EVB with a ColdFire micro on it, asking only that you pay shipping. The particular part in question (MCF51JM128) has I think 128K flash, 16K RAM and on-chip USB.

However, if the answer is 68k then the question may have been asked wrong; 68K/CF is more or less an obsolescent architecture these days. The impression I have from Freescale's literature is that CF exists only to provide a somewhat source-leve upward migration path from

68HC09 8-bit apps, without the cost [to Freescale] of an ARM license.
Reply to
larwe

Hey, that 09 (apparently you meant 08) typo can bring memories to some here (like myself, having grown up on a 6809 CPU, which has been dead for 20 years now).

The CF line - especially the tiny ones you refer to - is good enough on its own, I don't see it having anything to do with ARM. And the parts - debug interface included - are 100% documented (don't know how this is for ARM). Unlike ARM, programming CF in 68k assembly is quite practical - which is a huge difference (for those who can take advantage of it, admittedly not many).

Didi

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Reply to
Didi

Ladies,Gentlemen -

I knew something about Coldfire, but didn't know it had JTAG interface. Yes, I've done ASM programming and fully intend to use it again.

Now about assemblers ...

OK, the part lines up nicely enough, but where's the assembler from and at what cost?

2Penny

Didi wrote:

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Reply to
2Penny

Ouch, I think they have no JTAG - just a so called "1 wire debug interface" or something. It is documented but I have not dealt with it yet, including these parts in my toolchain is only on my TBD list... This pretty much means no boundary scan, I believe (again, not sure what can be done over the debug interface).

I can't help here since I use my own, DPS based toolchain which is not available for any popular hardware platform. Since you know 68k ASM I suppose you will either know you have to stay away from the weird GNU 68k syntax or be used to it and just use it... :-).

Didi

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d365366d1a7f3b4...

Reply to
Didi

You don't need to address the group so formally - but you *do* need to learn to post correctly (quote properly without extra indents, and don't top-post).

The Coldfires do not have a JTAG interface (some do, but it's not for debugging). They have a BDM interface which is a Freescale-specific serial debugging interface. It does a similar job to JTAG debugger interfaces, but is more efficient.

Get the gcc toolchain from

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This includes the gnu assembler and linker, gcc C and C++ compilers, a library, and other tools. You can get the completely free version (free as in beer and free as in speech), or pay for a supported version with integrated Eclipse and some extra utilities.

An alternative would be Code Warrior from Freescale, which is free for a limited code size.

Reply to
David Brown

That may be the impression *you* have got of the ColdFire, but it is totally at odds with reality. The ColdFire is very much a major 32-bit processor architecture with devices ranging from tiny low-power with integrated memories to superscaler devices at several hundred MHz. Freescale have a couple of dozen devices available, with new ones coming out all the time. The cores are also available for license - I read somewhere (but haven't confirmed) that there are more ColdFire cores in ASICs than in all of Freescale's MCF device range put together.

The ColdFire core bears no resemblance to the 8-bit Freescale cores - perhaps you are thinking only of the ColdFire v1 cores that are available in the same package and with the same peripherals as a range of 68S08 devices (the idea being that you can easily move between cheaper and lower power 8-bit cores and faster 32-bit cores).

I don't know that many people would describe the ColdFire as "PIC-like", however. When you mention "PIC", experienced embedded developers tend to think of nice peripherals and a horrendously ugly core, while people who know the ColdFire core think of it as one of the most elegant designs available (and with good peripherals too).

Reply to
David Brown

Mere availability of a wide range of devices is an orthogonal issue to the matter of obsolescence. ColdFire is used, yes, but (if you buy the reports) it's experiencing a shrinking number of design wins. Freescale as a whole isn't doing amazingly well these days, FTM.

... exactly like the popular cores, viz. ARM and MIPS. ColdFire occupies the same space for Freescale that AVR32 does for Atmel (and most of the other silicon vendors have their own proprietary 32-bit cores, too - NEC, ST, ...). They're generally available but not really what one would call mainstream.

Yes, that's what I meant. Wasn't implying any architectural similarity between the cores, I was talking about the migration path Freescale touts.

Reply to
larwe

Coldfire appeared after Motorola had closed the 68k line at 68060; to me it looks like extending the life of the 68k architecure which was so much ahead of its time that it is still hard to scrap. They wanted to replace it with the PPC - which is still by far the most advanced architecture on the market today - but 15+ years on this has yet to be 100% completed... Much of the reason - perhaps not quite recognized - is the fact that

68k assembly is an extremely efficient language. Extending that into VPA has made me even more efficient on PPC platforms, however this is not (perhaps yet) available for a wider audience. And using a 68k using C is more or less pointless, there is no advantage to have with that - just use PPC or ARM or whatever.

The tiny coldfires compete for the lowest power market segment, only the 430 is in that category. And CF has that true 68K style IRQ priority scheme, none of the rest have it (and very few poeople know what to do with it, of course).

Didi

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Reply to
Didi

Have been a long term fan of 68k and considering that it's been around since 1979'ish, has to be one of the longest lasting embedded 16 bit architectures around. A clean, orthoganal design with (as you say) a fully vectored prioritised interrupt subsystem that's hard to better 25+ years later. Renesas copied it almost verbatim in the M30870.. series and probably many others as well.

Looked at coldfire and wanted an excuse to use it, but can't ignore the logic of arm, which has dozens of vendors. Parts are cheap and powerfull as well and you just have to live with stuff like the idiosyncratic interrupt structure. Nothing like as clean as 68k, but I guess that's progress and still haven't really forgiven Freescale for eol'ing Dragonball 68k at pretty short notice...

Chris

---------------------- Greenfield Designs Ltd Oxford England

44 1865 750 681
Reply to
ChrisQ

One good thing about Coldfire is that the V1 IP is relatively cheap. I think it's 10K plus 1 penny each. So, if you are into ASIC, you can keep it alive for ever.

Reply to
linnix

The "dozens of vendors" thing is largely overestimated in its importance, not one ARM based part is really second sourced. The common thing they have is the core which also varies widely, like many others. Then the tiny CF (pretty new, some of them still just "sample") addresses the lowest power market (while you still have a 50 MHz 68k...), I don't know if ARMs do that.

Other than that, I also have looked at the CF line and rejected it about 8 or 9 years ago. It was just emerging, and I had to move on from the CPU32 (I used the 68340, still available, unlike your Dragonball...); my judgment was that my (huge amount of) code, written in CPU32 ASM would be better off using just source level compatibility rather than binary, the CF would have been a lot worse off emulating all the addressing modes it did not have than the PPC doing it at the expense of somewhat longer binaries (which turned out to become apr. 3.5 times larger than the original CPU32 ones, no optimization whatsoever - with much room for some). But the tiny CF parts - which are all

Reply to
Didi

How can they compare to a sub-$1 Cortex-M3 part with 64K flash, 16K RAM, and loads of peripherals?

Reply to
larwe

Perhaps someone familiar with both families could comment, I am not that familiar with ARM and you don't seem to be very familiar with CF. Actually I have yet to become very familiar with it myself, but I have already done some work in this direction. How much does the part you refer to consume running full power at 50 MHz core clock? The MCF51QE128 @3.3V, 50 MHz core/25 MHz bus specifies 33.4 mA - everything on and running, obviously it goes down through uA to nA range using different power saving modes. The prices I know of are for 1000+, are yours at 1000+ as well?

Didi

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Reply to
Didi

My point is that there needs to be a compelling reason to choose a proprietary core. I remember having the same argument in this NG about AVR32. The Atmel guys have given up on trying to sell it to us, when they come round to talk about products they just say "oh, and of course there's AVR32 as well". Microchip keeps trying to sell us the

32-bit PICs... which reminds me they were going to give me an EVB to play with at home. I must ping them about that.

The part isn't characterized at that precise frequency (it is characterized from 8 to 72MHz in various steps), but at 48MHz core, fbus=3Dfcore (but 1WS, effectively 24MHz) it's 36.1mA with all peripherals enabled, 24.4 with all peripherals disabled (running from flash) or 31.5/20.5mA running from RAM. Definitely the same ballpark.

That's why I got puzzled when you or someone else in this thread started talking about low power consumption; CF simply isn't amazingly slender in this day and age. Low-power apps that don't require much horsepower go with an 8-bitter or an MSP430; apps that do require number-crunching horsepower often use a low-power DSP these days.

We don't bother to get pricing for anything in quantities under

10000 :)
Reply to
larwe

I do not see how ARM is more mainstream than 68k, other than in marketeer talk. What do you get if your MCU is ARM based and not CF or whatever? It is still single sourced. There is likely more 68k code around than there is ARM - has been used much longer in much larger applications than ARM goes into. There must be some compelling reason nowadays with all that C programming mess to prefer a part based on its core anyway; access to an efficient assembly language for someone who can take advantage of it looks like one to me.

Same ballpark indeed, if the ARM based part has also the lowest power saving modes - slower internal clock etc. - this becomes even more so.

So prices are the same. Well, I am sure I could pack a lot more code into a CF part than anyone could pack using C in either ARM or CF (factor of 10+) and I would be faster practically for any project larger than something saying "hello world", so I know what my choice would be.

Didi

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Reply to
Didi

Availability of *new* devices is a good indication that are architecture is not obsolete (or going obsolete). I agree about *existing* devices, whose availability is, as you say, orthogonal to obsolescence. But no company will devote significant resources to making new products for a dying range (look at Freescale's MCore range, for an example).

I don't have any numbers for where the ColdFire stands in either the number of designs or number of parts, but I have seen nothing to indicate that it is not a major architecture, and will continue to be one.

Like the AVR32, and unlike the ARM, MIPS, PPC, and x86, the ColdFire is single-source. If by "mainstream" you mean "available from multiple sources", then the ColdFire is not mainstream. But if by "mainstream" you mean popular, easily available in small and large quantities, well supported by its manufacturer, distributors, and third-party tool developers (open source, small commercial, and big commercial vendors, for compilers, debuggers, OS's, software libraries, hardware development kits, etc.), then I think the ColdFire is mainstream.

Fair enough.

Reply to
David Brown

From the very start, the 68k had a 32-bit programming architecture. For cost reasons, the implementation used a 16-bit ALU and datapath, but all the registers were 32-bit, and all instructions supported 8-bit,

16-bit and 32-bit widths (even though the 32-bit versions took twice as many clock cycles). This meant that when 32-bit ALUs became economically feasible, the 68k just got faster with the same software, unlike the x86 architecture that got seriously ugly in the move to 32 bits.

There are lots of vendors of ARM devices, (almost) none of which are compatible with each other in terms of peripherals, pin outs, or pretty much anything except the core. For most developers, you don't choose to use ARMs - you choose to use Atmel ARMs or NXP ARMs, or whatever. There is not actually much of a difference between that and choosing the FreeScale ColdFires - you base the choice on things like peripheral mixes for particular devices, cost, distributors, tools, etc.

The Dragonball was always a special case for Freescale - it was a one-off device, not part of a family (though the core was), and aimed at a few specific large customers (such as Palm). When these customers moved on, 99% of the sales dried up. It's a different matter for devices like the 68332, which has a much wider range of customers. That device must be nearly 20 years, and Freescale have still not managed to EOL it despite trying for years to move customers to the MPC5xx line (PPC based) and the later MCF523x (ColdFire base, and much more popular among 68332 users).

Reply to
David Brown

In a way, we have to thank the x86 marketer for beating the 68k. Otherwise, many programmers would stay with assemblers and C would not be as popular. C masks out the ugly x86 architecture.

Reply to
linnix

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